(35b) Selective Electrocatalytic Activity of Ligand-Stabilized Copper Oxide Nanoparticles for CO2 Reduction and Methanol Oxidation

The chemical conversion and
utilization of CO₂ are extremely important catalytic challenges. The
electrochemical conversion of CO₂ over bulk copper has been widely
investigated, but questions about the reaction mechanism and the influence of
the catalyst surface still remain. For example, how will the presence and type
of oxidized surface species influence catalytic activity? We have found that
ligand-stabilized Cu₂O and CuO nanoparticles can function as
catalysts for the electrochemical conversion of CO₂ into CO. We show
that the ligand-stabilized Cu-oxide nanoparticles promote CO₂
conversion more efficiently than bulk copper, bulk copper oxide, and weakly or
non-ligand stabilized nanoparticles. Additionally the ligand-stabilized
Cu-oxide nanoparticles were also active towards methanol oxidation, with
approximately 88-100% selectivity for the conversion of methanol into formaldehyde.
On the other hand, bulk Cu-oxide catalysts exclusively produced CO₂.
Electron microscopy, electrochemistry, a variety of spectroscopic techniques
and chromatography have been used to investigate the catalyst structure, nature
of the active sites, and product distributions. Our data suggests that unique
reactive sites on the ligand-protected Cu-oxide nanoparticle surface promote
product selectivity.